AB1370 MICROVASCULAR CAPILLAROSCOPIC ABNORMALITIES AND AUTOANTIBODY OCCURRENCE IN SARCOIDOSIS PATIENTS.
Authors: F. Cattelan, E. Hysa, C. Pizzorni, M. Grosso, E. Barisione, S. Paolino, G. Pacini, G. Ferrari, A. Sulli, V. Smith, M. Cutolo
Journal: Annals of the Rheumatic Diseases (2022)

Background Sarcoidosis (S) is a granulomatous disease with multi-organ involvement displaying a mixed immune-mediated pathophysiology. Raynaud’s phenomenon (RP) has been occasionally reported in S patients [1] and serum positivity for autoantibodies has been detected in S patients but their significance is debated [2]. Objectives We described nailfold videocapillaroscopy (NVC) findings and estimated the prevalence of serum anti-nuclear (ANA) and extractable nuclear antigen autoantibodies (ENA-Abs) in S patients, comparing them with age- and sex- matched healthy controls (HCs) and patients with primary Raynaud’s phenomenon (PRP). Secondarily, we analysed potential correlations between NVC findings with the occurrence of autoantibodies, immunomodulatory treatment, laboratory parameters, variables of pulmonary function and whole-body imaging. Methods Twenty-seven (27) S patients, classified according to WASOG criteria[3], were assessed through NVC examination, laboratory parameters (including serum concentrations of angiotensin-converting enzyme [ACE], C-reactive protein [CRP], calcium, phosphorus, albumin, 25-hydroxyvitamin D, parathormone, ANA and ENA), pulmonary function tests (PFTs), chest-X ray and positron emission tomography/computerized tomography (PET/CT). Among NVC parameters, we analysed capillary dilations, giant capillaries, haemorrhages, nonspecific abnormalities, and capillary absolute number for mm [4]. Pulmonary involvement was classified by X-ray Scadding staging system (SSS) scoring S patients in 4 grades [5]. From PET data, the maximum standard uptake value (SUVmax) was quantified as a variable of tissue 18-fluorodeoxyglucose hyper-uptake: consequently, S patients were defined PET-positive when SUV value ≥ 2.5. NVC parameters and ANA/ENA dosage were recorded also in 30 PRPs and 30 HCs. Results We excluded, among the cohort of S patient, one participant having a systemic sclerosis in overlap with S. The remaining 26 S patients (mean age 56.5 ± 12.5 years, 53.8 % of females, disease duration 28.4 ± 55.1 months, 27% glucocorticoid-naïve) showed a significant higher rate of dilations and nonspecific abnormalities and a lower mean capillary absolute number than PRPs and HCs (p &lt; 0.01 for all comparisons). (Figure 1) The prevalence of ANA positivity was significantly higher in S patients compared with PRPs and HCs (p &lt; 0.02 for both). Among the whole cohort of patients only one S patient displayed a positive ENA-Ab (Ro52). In the analysis of S patients’ subgroup, a significant negative correlation was detected between serum ACE levels with the presence of capillary dilations (rho = -0.45, p = 0.04), between CRP and mean capillary absolute number (rho = -0.49, p = 0.02) and a positive correlation was also detected between the mean capillary absolute number and the forced vital capacity percentage (FVC%) (rho = 0.40, p = 0.04). Conclusion Our findings suggest a microvascular involvement in sarcoidosis whose investigation by NVC could be useful for the detection of an overlapping connective tissue disease and for the monitoring of the phenotypes of S patients displaying RP. The positivity for autoantibodies in S patients is in line with literature data suggesting, at least partially, autoimmune features of the disease or the production of autoantibodies reactive to tissue damage. The correlations between NVC findings with ACE levels and lung function variables generate hypotheses of a potential partial vascular impairment in sarcoidosis disease activity and lung involvement. References [1]Nigro A et al. Reumatismo 2004; 56: 278-81. [2]Kobak S et al. Autoimmune Diseases 2014 [3]Judson M.A et al. Clin Rev Allergy Immunol 2015; 49: 63-78. [4]Smith V et al. Autoimmun Rev 2020; 19: 102458. [5]Scadding J.G. Br Med J 1961; 2: 1165-72. Disclosure of Interests None declared